----- Original Message ----- > Secondly, if the 3.11-rc1 kernel is configured with CONFIG_SLAB, the crash > session will fail with a segmentation violation. Here is an example with a > crash version that has a bumped-up NR_CPUS and configured to use CONFIG_SLAB: > > # crash vmlinux vmcore > > crash 7.0.4rc17 > Copyright (C) 2002-2013 Red Hat, Inc. > Copyright (C) 2004, 2005, 2006, 2010 IBM Corporation > Copyright (C) 1999-2006 Hewlett-Packard Co > Copyright (C) 2005, 2006, 2011, 2012 Fujitsu Limited > Copyright (C) 2006, 2007 VA Linux Systems Japan K.K. > Copyright (C) 2005, 2011 NEC Corporation > Copyright (C) 1999, 2002, 2007 Silicon Graphics, Inc. > Copyright (C) 1999, 2000, 2001, 2002 Mission Critical Linux, Inc. > This program is free software, covered by the GNU General Public License, > and you are welcome to change it and/or distribute copies of it under > certain conditions. Enter "help copying" to see the conditions. > This program has absolutely no warranty. Enter "help warranty" for > details. > > GNU gdb (GDB) 7.6 > Copyright (C) 2013 Free Software Foundation, Inc. > License GPLv3+: GNU GPL version 3 or later > <http://gnu.org/licenses/gpl.html> > This is free software: you are free to change and redistribute it. > There is NO WARRANTY, to the extent permitted by law. Type "show copying" > and "show warranty" for details. > This GDB was configured as "x86_64-unknown-linux-gnu"... > > please wait... (gathering kmem slab cache data)Segmentation fault > > > Although I haven't tested recent CONFIG_SLAB kernels (Fedora and RHEL use CONFIG_SLUB > by default) I believe this is related to this patch-set that was pulled into > Linux 3.13: Further testing shows that the segmentation violation above will only occur in Linux 3.8 and later kernels if: (1) the kernel is configured with CONFIG_SLAB, and (2) the sum of the kernel's NR_CPUS and MAX_NUMNODES values exceed the NR_CPUS value compiled into the crash utility. That would be fairly unlikely, but it is true in with the "CONFIG_MAXSMP" setup I'm testing with now. Typically (2) above is not true, and the crash session will come up OK. However, the 3.13 "slab-overload" patch that I pointed to here: https://lkml.org/lkml/2013/10/16/155 From: Joonsoo Kim <> Subject: [PATCH v2 00/15] slab: overload struct slab over struct page to reduce memory usage Date: Wed, 16 Oct 2013 17:43:57 +0900 is the real issue at hand, because it will require a significant fix to support CONFIG_SLAB kernels. Thanks, Dave -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility